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As regulations become more stringent, transient fuel control becomes extremely important for meeting emissions requirements in a cost-effective manner. Significant modeling work has been performed for a variety of conventional gasolines in port fuel injected (PFI) engines. This paper describes an extension of previous modeling work for alternative fuels. The paper first details the application of a distillation model to create the multi-component fuel models used in the simulations. The fuel models are then used in the transient Four Puddle Model to simulate the coupled liquid fuel and thermal/thermodynamic processes in the engine. Simulation results from the model are compared with dynamometer data over a transient, warm-up test.

The physics of the mixture preparation process plays a critical role in transient engine control, a key enabler for satisfying increasingly stringent emissions requirements. This paper presents a fully transient, coupled model in Modelica for the liquid fuel behavior and thermodynamic engine cycle including thermal effects for a port fuel injection engine. Details of both the liquid fuel transport and cycle simulation models are provided. The integrated model is used to examine the effects of variable cam timing on the transient fuel behavior including comparisons between simulation results and experimental data under a variety of engine operating conditions.